The present invention relates to a method and an apparatus for measuring the “green-speed” of golf course greens. Green-speed more precisely is a measure of distance. It is a quantitative measurement of a green surface characteristic (green-speed), which relates to how far a golf ball rolls after being given a fixed initial speed (e.g. putted from an absolute reference stroke), and then using that quantity for green control, comparison and maintenance purposes. More particularly, the invention relates to an apparatus for measuring the green-speed of putting greens in a precise manner which improves on the current measuring practice.
The speed at which a golf ball rolls across a putting green toward the hole varies from golf course to golf course and sometimes from putting green to putting green on the same golf course. The faster the green-speed, the more skill is required to consistently hole putts in the least number of strokes. Golf course greens which have variations in green-speed between different greens or even differences in green-speed on the same green, require extraordinary skill on the part of the golfer to hole putts and usually result in considerably higher scores.
Ideally all golf greens on the same course are uniform with little variation in green-speed from one green to the next. Variances in green-speeds usually depend upon a wide variety of factors including maintenance procedures, grass types, weather conditions, number of rounds of golf played on the golf course and the skill level of golfers using the golf course, among others. For example, public golf courses with a large number of rounds and with a relatively large number of limited skill players tend to have green-speeds which are slow (between 6-8). Most upscale public golf courses and private golf clubs have greens with somewhat faster green-speeds (between 8.5-10). Courses which are used for tournament play, particularly professional tournaments, have green-speeds which are considerably faster (between 10.5-14).
Since 1976, in order to aid golf course superintendents to keep green-speeds consistent, and/or to regulate the green-speed for a particular event or playing condition, the green-speed of greens traditionally has been measured using a standard device called a Stimpmeter. This device was developed by Edward Stimpson to provide a standard device to consistently release a number of golf balls, one at a time, at a constant initial energy onto a green, to allow quantitative measurement of green-speed. The Stimpmeter is designed to be used on a wide variety of courses and for a wide variety of green conditions.
The Stimpmeter is a thirty-six inch long, straight aluminum bar with a V-shaped channel along its length, with a milled notch adjacent the upper portion of the V-shaped channel to accommodate a golf ball. The lower end of the Stimpmeter is provided with a beveled edge, which engages the surface of the green. In use, the beveled end of the Stimpmeter is placed on the green surface and a golf ball is placed in the notch. The Stimpmeter is designed so that a golf ball will be released and start to roll down the V-shaped channel when the notch end of the Stimpmeter is raised, by hand, to an angle of approximately 20 degrees, and then held absolutely still once the ball starts to roll down the ramp.
The United States Golf Association (USGA) specifies that to measure green-speed, three balls are sequentially rolled from a Stimpmeter over a relatively flat part of a green, in a first direction and the average roll distance measured. The test is repeated with the balls rolling over the same area, in the opposite direction. The average distance of all six rolls then represents the green-speed. This USGA specified Stimpmeter measurement has been the standard for many years and is recognized, not only by golf course superintendents, but also by the various local, national and international golf associations.
The design of the Stimpmeter often produces a number of inaccuracies in green-speed measurement. The release height of a golf ball placed in the notch in the V-shaped channel depends upon the dimple configuration and exact placement position of the golf ball relative to the edge of the notch. This causes errors in the initial speed of release of balls onto the green surface, which in turn, cause direct errors in green-speed measurements. Operator error, such as lifting or raising the bar in a jerky motion or not holding the bar steady as the ball rolls during a test may also cause a relatively large variation in roll distance. The flat sides of the V-shaped channel often causes golf balls rolling on dimple flats to chatter and bounce against the sides of the channel, which also affects roll distance. Because balls impact the green surface at the lower end of the Stimpmeter at a 20 degree angle, they bounce, thereby creating further variables in roll distance. Three balls are used, each rolled from the same spot in the same direction, and frequently a ball roll track is formed in the grass on the green, causing roll distances to be erroneously longer with each successive ball rolled in a previous ball track. Still further, the Stimpmeter is unable to detect slopes in the surface of the greens to be measured.
The prior art, other than the Stimpmeter, is mostly silent with respect to devices for reading green-speed.
U.S. Pat. No. 3,215,436 to Carter, directed to a green surface, shows a green-speed measuring device with a V-shaped ball channel supported at an angle of 30 degrees on a tripod support. The lower end of the track is formed with curved extensions tapering to a point. A golf ball is released down the channel. The distance the ball rolls is used to create a coefficient of putting friction which represents the green-speed of the putting surface.
U.S. Pat. No. 5,358,446 to Bergman shows a ramp used to roll a bowling ball with a lower forward rail portion which is horizontal to the alley surface.